Mapping of asperities and estimation of spatiotemporal distribution of interplate slip

粗糙体测绘和板间滑移时空分布估计

基本信息

批准号：
15204037
负责人：
HASEGAWA Akira
金额：
$ 26.21万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

In this research, we have been aiming to analyze details of lock and slip on the plate boundary under the Pacific Ocean in NE Japan and to understand the generation mechanism of interplate earthquakes. The main research contents are: 1. analysis of repeating earthquakes, 2. analysis of source process of medium ＆ large earthquakes based on broadband seismic waveform data, 3. GPS data analysis, 4. research on the property of asperities by using numerical simulation.According to the result of 1. analysis of repeating earthquakes, we successfully estimated the time variation of interplate slips around the rupture zone of the 2003 Tokachi-oki earthquake, by identifying the repeating earthquakes in all parts of the plate boundary under the Pacific Ocean from Hokkaido to NE Japan. As for the 2. analysis of source process based on seismic waveform data, we showed that the rupture area of Miyagi-oki earthquake (M7.2) on Aug. 16, 2005 is overlapped with the southeastern part of the rupture area … More of the 1978 Miyagi-oki earthquake. So, this means that the asperities of the 1978 earthquake located in the north and west part are left unruptured; our research pointed out the importance of continued and careful observation on this area. Moreover, we conducted reanalysis of aftershocks of Miyagi-oki earthquakes with magnitude >7 in 1930s, and found out that three asperities could have slipped separately, in three times, in the case of 1930s' Miyagi-oki earthquakes. With 3. GPS analysis, after 2005 Miyagi-oki earthquake, we detected the after slip which spread toward south of the rupture area of the event. This observation result corresponds with the result of seismic-waveform inversion analysis; the northern and western asperities are left unruptured. The result of 4. numerical simulation analysis shows that, in order to explain the propagation velocity of the after slip observed in the deep plate boundary close to land, pore pressure around the plate boundary should be extremely large. On the other hand, in order to explain the propagation velocity of the after slip observed in the shallow plate boundary close to the trench, large pore pressure is not necessary like in the case above. These results suggest the depth variation in the amount of water supplied to the plate boundary, which was caused by dehydration reaction, or the depth variation in coefficient of permeability around the plate boundary.As mentioned above, through this research, we have achieved substantial results to enhance understanding of the generation mechanism of interplate earthquakes. Less

在这项研究中，我们的目标是分析日本东北部太平洋下板边界上锁定和滑倒的细节，并了解板间地震的发电机理。主要研究内容是：1。对重复地震的分析，2。基于宽带地震波形数据的中等和大地震的源过程分析，3。GPS数据分析，4。通过使用数值模拟的依赖性的研究。按数值模拟进行1。对1的结果进行1。重复地震的分析，我们成功地估计了围绕跨度的层次变化，我们围绕着跨度的时间变化。通过确定从北海道到日本东北的太平洋下方各个地方的重复地震。至于基于地震波形数据的2。分析源过程，我们显示了2005年8月16日的Miyagi-Oki地震（M7.2）的破裂区域与破裂区的东南部重叠……更多1978年Miyagi-Oki地震。因此，这意味着，位于北部和西部的1978年地震的森林震荡没有破裂。我们的研究指出了对这一领域的持续和仔细观察的重要性。此外，我们对1930年代的宫基 - OKI地震进行了重新分析，并发现在1930年代的Miyyagi-Oki地震中，三次可能在三次分别切下三个浅层。通过3。GPS分析，在2005年宫基 - OKI地震后，我们检测到了事件破裂区域以南的后滑动。该观察结果结果与地震波化基础架构分析的结果相对应。北部和西部的阳光不足。 4。数值模拟分析的结果表明，为了解释在靠近土地的深板边界中观察到的后滑动速度的传播速度，板界周围的孔压力应极大。另一方面，为了解释在靠近沟槽的浅板边界中观察到的后滑动的传播速度，就像上面的情况一样，不需要大孔压力。这些结果表明，由脱水反应引起的水量的深度变化，或板界周围渗透率系数的深度变化引起的。如上所述，通过这项研究，我们取得了实质性的结果，以增强对板层地震机制的发电机制的理解。较少的